By Deb Soule
Ginkgo biloba is thought to be the oldest living genus of seed plants on our planet and is the only member of the genus Ginkgo. Its family is Ginkgoaceae. Botanists who study the evolution of plants through their fossil remains have found that ginkgo has remained unchanged for the past 150 million years. During the time of the dinosaurs ginkgo grew in North America. The petrified remains of one of the largest ginkgo forests is near Vantage, Washington, on the banks of what is now the Columbia river.
Ginkgos came close to extinction during the last ice age but, fortunately, survived in China and other parts of Asia. In Japan ginkgo trees began to be planted around monasteries approximately 1000 years ago and these trees are still alive. Ginkgo has a reputation for being able to resist insects, pollution, viruses, bacteria, dust, wind, salt and old age, which is why it is so commonly planted along city streets. Fore Street, in the Old Port area in Portland, has been lined with ginkgo trees for several years. Last summer I noticed 10 to 12-foot-tall trees being planted in the median strip on Rt. 17 in Augusta, parallel to the Capital Mall Shopping Center. When these trees leafed out they held the unmistakable ginkgo leaf.
The leaves of ginkgo are a unique fan-shape and two-lobed (hence ‘biloba’) with many parallel veins. In summer the leaves are a beautiful vibrant green; they turn yellow in the fall. I am told that the ginkgo tree drops all its leaves at once in the autumn. What fun it would be to stand under an old, 80-foot-tall ginkgo and be showered with its golden leaves.
Ginkgo trees are fairly slow growing for the first 20 years, reaching a height of 20 to 30 feet. As they mature they reach 50 to 80 feet, spreading their branches outward 20 feet in every direction. Ginkgo can be started from seed by placing the freshly gathered seed in moist sand in a plastic bag and storing it in the refrigerator for several months. In the spring, plant the seeds indoors in a quality soil mix. Female trees produce seeds after 20 to 50 years. Their fruits smell like rancid butter, or worse, which is why some people prefer to plant only male trees. However, the nuts are delicious and medicinal.
Ginkgo was brought to England as an ornamental in 1754 and to North America around 1784. Different cultivated varieties can be purchased from nurseries, with sexed trees being more expensive. Fedco Trees sells unsexed trees.
Ginkgo, which is hardy to -20 to -35˚ F., is easy to grow and requires little maintenance. It prefers sun and moist, sandy, sweet soil, but is adaptable. Perhaps patience and reverence are most needed when growing ginkgos. Besides being able to live for hundreds of years, ginkgos were the only trees that remained alive after the bombs were dropped in Hiroshima and Nagasaki. Their ability to tolerate environmental toxins, especially from something as deadly as a nuclear bomb, is of great significance in today’s extremely polluted world.
The living plants themselves guide me as to how best to use the medicine they offer us. Since ginkgos survived the bombs and have demonstrated their ability to live such lengthy lives, they keep coming to mind among a handful of herbs that may support our immunity and stamina as we face the seriousness of dioxins and pesticides contaminating our immediate environment.
Ginkgo leaf is considered to be an antioxidant, helping prevent damage to the tissues of our body from free radicals. It can improve blood circulation and counteract cellular damage that occurs when excess free radicals in the body are created during chronic activation of the immune system. This is the protective mechanism we need as we are constantly exposed to environmental toxins, such as dioxins, radiation and pesticides, and to such emotional stressors as overwork, unhealthy working environments and stressful homelives. Cell membranes are especially vulnerable to free radical damage, which can lead to the death of the entire cell. Ginkgo is invaluable to us because it protects cell membranes in the brain and other tissues throughout the body.
In Europe, many clinical studies have been done on the medicinal benefit of ginkgo leaves which are widely prescribed there by physicians for people with decreased blood flow to the brain, such as those with short term memory loss, lack of concentration, and a decrease in intellectual ability, vision, equilibrium and balance. Because ginkgo leaf increases the uptake and utilization of oxygen and glucose in tissues throughout the body, much interest exists in using it for the early stage of Alzheimer’s disease: it can increase blood flow to the brain and regulate neurotransmitters that help prevent memory loss, depression and senility.
Ginkgo leaf is being used specifically for people with tinnitis, ringing in the ear, and it can protect the ear from damage due to loud noises or infections and restore impaired hearing loss. It has helped people who have a sudden hearing loss or a hearing weakness because of poor blood circulation.
People who suffer from eye disorders in which the retina has been damaged may benefit from daily use of ginkgo leaf over several months because of its ability to improve circulation. Ginkgo is being given to some diabetic patients by their physicians to help protect the retina and prevent loss of vision.
Ginkgo can block a compound called platelet-activating factor (PAF). PAF is involved with activating various kinds of endothelial and immune cells that secrete chemicals that enhance the blood-clotting process and create inflammation. Although this process is important, European research shows that PAF may contribute to some cases of asthma. The release of PAF from immune cells in response to pollen, dust and other allergens can cause constriction and inflammation in the bronchial airways resulting in limited or restricted breathing. The ginkgolides A, B and C found in a standardized extract of ginkgo leaf look like a possibility for reducing bronchial constriction and the frequency and severity of asthmatic attacks. Ginkgo is certainly an herb for people with asthma to investigate further.
Ginkgo is also being used to improve circulation for people with bedsores, Raynaud’s Syndrome, strokes or head injuries. Ginkgo helps dilate the vessels to the brain, so people suffering from headaches when the head feels like it is in a vice will appreciate standardized capsules of ginkgo – along with addressing possible root causes.
Attention Deficit Disorder (ADD) is an increasingly common diagnosis for children, and the drug ritalin is often prescribed. Fortunately, more doctors are considering quality ginkgo leaf tinctures of standardized capsules for children with ADD. My neighbors 13-year-old son, who was diagnosed last year with ADD is doing very well on ginkgo. Diet also plays an important role in lessening the challenging symptoms associated with this disorder.
Edible, Medicinal Nuts
Traditionally, herbalists trained in Chinese medicine do not separate food and medicine the way westerners do. Ginkgo nuts have a pleasant sweet and bitter taste and have a history of being eaten regularly because of their overall strengthening and tonic properties. Specifically the nuts are considered to be a kidney yang tonic, and help restore hearing loss, stop bed-wetting, soothe bladder irritation, lessen frequent urination and cloudy urine, strengthen weakened lungs and ease coughs and asthma. Avoid eating the nuts when an acute infection is present and the body is overheated. Raw nuts are toxic and need to be cooked. Often they are cooked in rice and served with honey. If you have access to a female tree that produces nuts, be aware that aside from the foul odor, the pulp of the nuts can irritate the skin, similar to poison ivy or oak. Use gloves if you are removing the pulp in order to collect the nuts for food. The raw nuts must be cooked. Fortunately the leaves to not contain any chemical substances that irritate the skin.
Ginkgo has many beneficial attributes and research has shown that when using a preparation of the whole leaves or cooked seeds within the recommended dose range, no known toxicity occurs. People using a standardized extract of ginkgo for more serious health conditions need to stay in regular contact with their health care provider, who can monitor their improvement and regulate dosage. (I consider standardized extracts to be botanical drugs because they have been manipulated in a lab to concentrate certain chemicals.) Ginkgo leaf products need to be avoided by people who have extreme hypertension, a history of aneurisms, or vascular over-sufficiency with a feeling of fullness.
We collect and tincture ginkgo leaves as they begin to turn golden in October. Some people like to gather and tincture the spring, summer and fall leaves and mix the different tinctures together at the end of the year. If you have the space, plant a few ginkgo trees and watch them grow. Ginkgo is a special tree because it is so ancient. Sitting near the tree may offer you helpful insights because it is truly an Elder in the tree community.
About the author: Deb owns Avena Botanicals in West Rockport, Maine, and is author of The Roots of Healing: A Woman’s Book of Herbs.